There’s a moment in “Rock of Ages,” right at the beginning, even before the completion of the opening credits, where the film verges dangerously close to being uber-cheesy. Julianne Hough is singing the most sterile version of “Sister Christian” you’ve ever heard, on a bus, perfectly lit, sitting alone (as buses from Oklahoma always lack for riders), with a Cheshire smile permanently affixed. She sings by herself … right up until the moment when the rest of the bus joins in, somehow surprising her, as she thought bus singing was primarily a personal pursuit. It’s then you realize what you’re truly in for, and the film pivots from “potentially cheesy” to a “river of gooey cheese with Julianne Hough as Captain Cheese, aboard the S.S. Muenster”.

Yes, “Rock of Ages” is a film that’s completely in on the joke, leading to the occasional smirk, though you’ll beg for some new casting before the end credits roll. You’re officially motoring, though I’m not sure of the current price for flight.

Hough plays Sherrie Christian, a small-town girl looking to make it big in Los Angeles. She’s immediately mugged (and that part I can vouch for the veracity of) and then offered a job at the hottest rock club on the strip, The Bourbon Room. Befriended by a boy named Drew (Diego Boneta), the two compete for who can rock the most feathery hair (Drew wins). Drew works at the bar too, though he has bigger dreams of being a rock legend. So too, does Sherrie, who (I guess) also wants to be a singer, though we basically never see her practice or yearn to perform. The whole Sherrie – Drew dynamic is troublesome, never fully sold, a detriment to the momentum of the plot overall. The duo duets with great frequency, but it’s not until the end that the film figures out, “Wait, we should just make fun of these two.” Once that decision is made, they become more palatable, but it’s a long and rocky ride to get there. Though Sherrie-Drew is the main plot point, there are two others that the film tracks along with. We should broach those two story lines before we run out of Internet ink.

Catherine Zeta-Jones is Patricia Whitmore; she’s the mayor’s wife, and she hates that rock n’ roll. It’s her goal to shut down the entire Los Angeles rock scene! And that’s about it, that’s the whole point of her existence, as a foil to music who just so happens to also sing and dance throughout. Sure, okay, we can go with that, except for the fact that almost every scene is barely held together by music, which may or may not have something to do with the preceding scene. Where great musicals like “Moulin Rouge!” and “Chicago” have a storyline that’s thoroughly enhanced by the music, “Rock of Ages” is comprised of inorganic moments that simply don’t fit. They’ll go from Bon Jovi’s “Dead or Alive” to Extreme’s “More Than Words” (which, not for nothing, isn’t from the ’80s) without anything resembling cohesion. It’s an extended karaoke session, though admittedly it features some fun mash-ups and performances. Your enjoyment of the film will come down to your enjoyment of the songs. Like an extended episode of “Glee,” or the less- awful parts of “Coyote Ugly”.

Which brings us to the strength of “Rock of Ages,” Thomas Cruise Mapother IV. This guy crushes every moment he’s in, and the shared scenes with Malin Akerman really work, to where you almost forgive her for “Watchmen.” Cruise, as Stacee Jaxx, is the living embodiment of a rock god. Ladies love him, and fellas want to be him, which, given our current rock god scarcity, really works. Tom Cruise is the closest thing we have to a legit “dangerous” rock star in his own right, so his presence in the film is a huge asset. He’s generally drunk, usually callous, and completely self-absorbed. It’s excellent. To balance him out, Akerman plays a reporter from “Rolling Stone” named, ahem, Constance Sack. She’s scheduled to interview Jaxx, it all goes awry, and these are the moments that feel the most like a real film, as their dynamic is at once hilarious and compelling.

“Rock of Ages” is the rare film where the trailer alone probably tells you all you need to know. If you commit to just having fun with it, and realize this isn’t a “musical” in the artistic sense of the word, then this won’t be a bad time. Movie aficionados are the most likely to admire Cruise’s performance and overlook the rest. “Rock of Ages” is a composite of scenes loosely gathered together and branded as a whole. If you’re not liking a particular moment or song? Never fear, they’ll be moving on to another track in a minute or two.